Cutting tool comprising toolholder and round cutting insert and method for repositioning the round cutting insert in a pocket of the toolholder

ABSTRACT

A cutting tool including a toolholder and a round cutting insert for mounting on a pocket floor of the toolholder. The toolholder includes the toolholder pocket floor having a bore therein and a plurality of grooves in the pocket floor arranged radially about the bore, wherein adjacent grooves are radially offset by a groove offset angle x. The round cutting insert includes an upper surface having a cutting edge, a lower surface opposite the upper surface, an exterior side surface between the upper surface and the lower surface, an interior side surface defining an aperture extending from the upper surface to the lower surface, and a plurality of lugs arranged radially about the aperture, wherein adjacent lugs are radially offset by a lug offset angle y, and wherein a ratio of y:x is an integer greater than or equal to 2.

FIELD

The present application relates to the field of cutting tools comprisinground cutting inserts, and in particular, to anti-rotation mechanismsfor the same.

BACKGROUND

Cutting inserts used in cutting tools such as milling cutters aretypically mounted in complementary-shaped pockets spaced around aperiphery of a tool body. The cutting inserts are typically securedwithin their respective pockets by screws inserted through an apertureprovided in the center of the cutting insert. During a cuttingoperation, such cutting inserts often experience not only compressiveand vibratory forces, but some amount of torque due to the angle betweenthe cutting edges of the cutting inserts and the workpiece. For cuttinginserts of non-round shapes, such torque does not result in rotation ofthe cutting insert due to the interference-type fit between the angledexterior sidewalls of such cutting inserts and the complementary-shapedwalls of the pocket that receive them. By contrast, round cuttinginserts can rotate within their respective pockets since no suchmechanical interference naturally arises between the exterior sidewallsof round cutting inserts and walls of the pockets which receive them.

To prevent such unwanted rotation of round cutting inserts, severalanti-rotation mechanisms have been developed previously.

In an example, a single lug is provided on a pocket of a toolholder toengage with one of a plurality of grooves on a round cutting insert toretain the round cutting insert against rotation. As the correspondingportion of the cutting edge of the round cutting insert is worn by thecutting operation, the round cutting insert is repositioned such thatthe lug engages with another one of the plurality of grooves to exposean unworn portion of the cutting edge of the round cutting insert to thecutting operation. Such round cutting inserts are provided with adifferent number of grooves (e.g. 4, 6, 8) depending on the desireddepth of the cut. However, during machining, a heavy feed tends to causedamage to or even remove the single lug from the pocket, thus reducingthe life of the round cutting insert and ruining the tool holder.

In another example, a plurality of lugs (e.g. 4, 6, 8) are provided on apocket of a toolholder to engage with a corresponding plurality ofgrooves (e.g. 4, 6, 8) on a round cutting insert to overcome the problemwith damaging a single lug. However, the toolholder is limited to usewith a cutting insert having the same number of grooves as the number oflugs on the pocket of the toolholder.

Thus, there is a need for an anti-rotation mechanism for round cuttinginserts which overcomes the problems of the prior art.

SUMMARY

In one embodiment, a cutting tool includes a toolholder and a roundcutting insert for mounting on a pocket floor of the toolholder. Thetoolholder includes the toolholder pocket floor having a bore thereinand a plurality of grooves in the pocket floor arranged radially aboutthe bore, wherein adjacent grooves are radially offset by a grooveoffset angle x. The round cutting insert includes an upper surfacehaving a cutting edge, a lower surface opposite the upper surface, anexterior side surface between the upper surface and the lower surface,an interior side surface defining an aperture extending from the uppersurface to the lower surface, and a plurality of lugs arranged radiallyabout the aperture, wherein adjacent lugs are radially offset by a lugoffset angle y, and wherein a ratio of y:x is an integer greater than orequal to 2.

In another embodiment, a method for repositioning the round cuttinginsert in the toolholder pocket includes unfastening the round cuttinginsert from the toolholder pocket, rotating the round cutting insert bya rotation angle z, and fastening the round cutting insert in thetoolholder pocket. The rotation angle z may be, for example, about 45degrees, about 60 degrees, or about 90 degrees.

In yet another embodiment, a toolholder includes a pocket floor having abore hole therein, and a plurality of grooves in the pocket floorarranged radially about the bore hole, wherein adjacent grooves areradially offset by a groove offset angle x.

In yet another embodiment, a round cutting insert includes an uppersurface having a cutting edge, a lower surface opposite the uppersurface, an exterior side surface between the upper surface and thelower surface, an interior side surface defining an aperture extendingfrom the upper surface to the lower surface, and a plurality of lugsarranged radially about the aperture, wherein adjacent lugs are radiallyoffset by a lug offset angle y.

Other embodiments of the disclosed cutting tools will become apparentfrom the following detailed description, the accompanying drawings andthe appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cutting tool according an exemplary embodiment of thepresent description, including a toolholder a round cutting insert, anda fastener.

FIG. 2 is a top view of a pocket of the toolholder of FIG. 1 .

FIG. 3 is a top perspective view of the pocket of FIG. 2 , includingsection line A-A.

FIG. 4 is a top view of the round cutting insert of FIG. 1 .

FIG. 5 is a bottom view of the round cutting insert of FIG. 4 .

FIG. 6 is a bottom perspective view of the round cutting insert of FIG.4 , including section line B-B.

FIG. 7 is a sectional view of FIGS. 3 and 6 along section lines A-A andB-B.

FIG. 8 is sectional view of FIGS. 3 and 6 along section lines C-C andD-D and including a fastener, in a fully fastened state.

FIG. 9 is sectional view of FIGS. 3 and 6 along section lines C-C andD-D and including a fastener, in a partially unfastened state.

DETAILED DESCRIPTION

FIG. 1 illustrates a cutting tool 10 according an exemplary embodimentof the present description. The cutting tool 10 includes a toolholder100 and a round cutting insert 200. The cutting tool 10 may furtherinclude a fastener 300.

The toolholder 100 as illustrated in FIG. 1 is exemplary. It will beunderstood that the toolholder 100 of the present description caninclude any toolholder 100 capable of holding the round cutting insert200 of the present description.

Referring to FIG. 1 , the toolholder 100 includes a toolholder body 102.As illustrated, the toolholder body 102 has the form of a toolholderbody for a milling cutter but may have the shape of a toolholder bodyfor any other cutting tool capable of holding the round cutting insert200 of the present description. The toolholder body 102 may, forexample, include a toolholder shank 104 and a toolholder face 106. Thetoolholder material may be made of any material not inconsistent withthe objectives of the present description.

Referring to FIG. 1 , the toolholder body 102 includes a toolholderpocket 110. The toolholder pocket 110 may include any structureconfigured for receiving the round cutting insert 200 of the presentdescription. As shown, the toolholder pocket 110 may be formed into thetoolholder body 102. The toolholder pocket 110 is configured to retainthe round cutting insert 200 therein. The toolholder body 102 mayfurther include one or more additional toolholder pockets 110 forholding one or more additional round cutting inserts 200.

Referring to FIG. 1 , the toolholder pocket 110 includes a pocket floor112 having an bore 114 therein. The bore 114 may be threaded forreceiving a threaded fastener 300. The toolholder pocket 110 may furtherinclude a pocket sidewall 115 for supporting the round cutting insert200 during a cutting operation.

Referring to FIGS. 2 and 3 , a plurality of grooves 120 in the pocketfloor 112 are arranged radially about the bore 114. As shown, theplurality of grooves 120 are arranged about only a portion of the entireperiphery of the bore 114. Alternatively, the plurality of grooves 120may be arranged about the entire periphery of the bore 114. Adjacentgrooves 120 of the plurality of grooves 120 are radially offset by agroove offset angle x.

The plurality of grooves 120 may be formed into a raised island 116 thatis raised relative to a base 118 of the pocket floor 112. As shown inFIGS. 1 to 3 , the raised island 116 may be positioned about only aportion of the bore 114. Alternatively, the raised island 116 may bepositioned about the entire periphery of the bore 114. The base 118 maytypically take the form a generally planar surface. The raised island116 may facilitate manufacturability of the pocket floor 112. During amanufacturing of the pocket floor 112, the raised island 116 may beinitially formed without the plurality of grooves 120. Thereafter, theplurality of grooves 120 may be substractively formed (e.g. machined)into the raised island 116.

Referring to FIGS. 2, 3, and 7 , the plurality of grooves 120 may bedefined by a plurality of segments 121 positioned between the pluralityof grooves 120. Each segment 121 may include a first segment engagementsurface 122 and a second segment engagement surface 123 opposite thefirst segment engagement surface 122. Thus, the first segment engagementsurface 122 of one segment 121 and a second segment engagement surface123 of an adjacent segment 121 may define a groove 120 positionedtherebetween.

The upper edge of the first segment engagement surface 122 and the upperedge of the second segment engagement surface 123 may define a maximumangular segment width 126, which is defined in terms of degrees aboutthe bore 114. In an aspect, the maximum angular segment width 126 ofeach segment 121 may be less than the groove offset angle x tofacilitate a maximum density of segments 121 positioned on the pocketfloor 112 and to avoid interference of the segments 121 with the cuttinginsert 200.

Each segment 121 may further include an inner end 124 proximate the bore114 and an outer end 125 opposite the inner end 124. In an aspect, thefirst segment engagement surface 122, the second segment engagementsurface 123, the inner end 124, and the outer end 125 may includeslanted surfaces to provide for an increased resistance of the segments121 against damage during operation of the cutting tool 10. In anaspect, the outer end 125 may have a higher width than the inner end 124to facilitate a decreased maximum angular segment width 126 of eachsegment 121.

FIGS. 4 to 6 illustrate an exemplary round cutting insert 200 accordingto the present description.

The cutting insert 200 may be formed of any material not inconsistentwith the objectives of the present description. Exemplary materialsinclude cemented carbide, carbide, polycrystalline diamond,polycrystalline cubic boron nitride, ceramic, cermet, steel or otheralloy. In a specific example, the substrate is formed of cementedcarbide. A cemented carbide substrate may include tungsten carbide (WC).WC can be present in any amount not inconsistent with the objectives ofthe present description. For example, WC can be present in an amount ofat least 70 weight percent, in an amount of at least 80 weight percent,or in an amount of at least 85 weight percent. Additionally, a metallicbinder of cemented carbide can include cobalt or cobalt alloy. Cobalt,for example, can be present in a cemented carbide substrate in an amountranging from 1 weight percent to 15 weight percent. In some embodiments,cobalt is present in a cemented carbide substrate in an amount rangingfrom 5-12 weight percent or from 6-10 weight percent. Further, acemented carbide substrate may exhibit a zone of binder enrichmentbeginning at and extending inwardly from the surface of the substrate.Cemented carbide substrates can also include one or more additives suchas, for example, one or more of the following elements and/or theircompounds: titanium, niobium, vanadium, tantalum, chromium, zirconiumand/or hafnium. In some embodiments, titanium, niobium, vanadium,tantalum, chromium, zirconium and/or hafnium form solid solutioncarbides with WC of the substrate. For example, the substrate caninclude one or more solid solution carbides in an amount ranging from0.1-5 weight percent. Additionally, a cemented carbide substrate caninclude, for example, nitrogen. In an aspect, the cutting insert 200 maybe a coated body, including one or more coatings.

The round cutting insert 200 includes an upper surface 210 having acutting edge 211, a lower surface 220 opposite the upper surface 210, anexterior side surface 230 between the upper surface 210 and the lowersurface 220, and an interior side surface 240 defining an aperture 241extending from the upper surface 210 to the lower surface 220. When theround cutting insert 200 is mounted onto the toolholder body 102 of thetoolholder 100, the lower surface 220 of the round cutting insert 200engages with the pocket floor 112 of the toolholder 100, and theexterior side surface 230 is proximate to the pocket sidewall 115 of thetoolholder 100.

As shown in the illustrated example of FIGS. 4 to 6 , the upper surface210 may be generally planar and terminate in a circular cutting edge 211surrounding the upper surface 210. However, the upper surface 210 is notnecessarily limited to the illustrated form.

Referring to FIGS. 4 to 6 , the radius of the upper surface 210 may begreater than a radius of the lower surface 220. Also, the exterior sidesurface 230 may have a shape that is complimentary to the shape of thepocket sidewall 115, typically a frustoconical shape. However, theexterior side surface 230 is not necessarily limited to the illustratedfrustoconical shape.

The interior side surface 240 defines aperture 241 that is centrallydisposed through the round cutting insert 200. As shown to FIGS. 7 and 8, a fastener 300 (e.g., screw) may be inserted through the aperture 241and bore 114 to secure the cutting insert 200 to the toolholder 100within the toolholder pocket 110.

Referring to FIGS. 5 and 6 , a plurality of lugs 221 on the lowersurface 220 are arranged radially about the aperture 241. Preferably,the plurality of lugs 221 are arranged about the entire periphery of theaperture 241. Adjacent lugs of the plurality of lugs 221 are radiallyoffset by a lug offset angle y. In an aspect a ratio of the lug offsetangle y to the groove offset angle x is an integer greater than or equalto 2. Preferably, as in the illustrated example, the ratio of the lugoffset angle y to the groove offset angle x is 2. In an alternativeexample, the ratio of the lug offset angle y to the groove offset anglex may be 3. In another alternative example, the ratio of the lug offsetangle y to the groove offset angle x may be 4.

By selecting the ratio of the lug offset angle y to the groove offsetangle x to be an integer greater than or equal to 2, the plurality oflugs 221 may be positioned within the plurality of grooves 120 such thatthe cutting insert 200 may be rotated with respect to the toolholderpocket 110 in small amounts defined by the groove offset angle x. Thus,the minimum amount of rotation of the cutting insert 200 is limited bythe groove offset angle x rather than by the lug offset angle y.Manufacturing the plurality of grooves 120 to have a small groove offsetangle x may easier than manufacturing the plurality of lugs 221 to havea small lug offset angle y. Therefore, by limiting the minimum rotationof the cutting insert by only the groove offset angle x, the presentdescription provides for a cutting tool 10 having a low minimum rotationof the cutting insert 100 while minimizing difficulties of manufacturingof the cutting insert 100.

In an aspect, the groove offset angle is in a range of from 7 to 17degrees. In a first example, the groove offset angle is in a range offrom 7 to 9 degrees, preferably 7.5 degrees. In a second example, thegroove offset angle is in a range of from 9 to 11 degrees, preferably 10degrees. In a third example, the groove offset angle is in a range offrom 14 to 16 degrees, preferably 15 degrees. A groove offset angle ofabout 7.5 degrees or about 15 degrees is beneficial because the 7.5 or15 degree groove offset angle enables for rotation of the cutting insert200 in standard amounts of 90 degrees, 60 degrees, and 45 degrees, whichprovides for 4 rotations (360 degrees/90 degrees), 6 rotations (360degrees/60 degrees), and 8 rotations (360/45 degrees). The groove offsetangle of 7.5 degrees would provide for additional flexibility in theangles of rotation of the cutting insert upon repositioning, and thegroove offset angle of 15 degrees would provide for ease ofmanufacturing of the lugs and grooves in the cutting insert and pocketfloor. A groove offset angle of about 10 degrees would enables forrotation of the cutting insert 200 in amounts of, for example, 90degrees, 60 degrees, and 40 degrees, which provides for 4 rotations (360degrees/90 degrees), 6 rotations (360 degrees/60 degrees), and 9rotations (360/40 degrees).

The cutting insert 200 would provide for replacement of conventionalround cutting inserts that have a defined number of grooves therein forengaging with a corresponding number of lugs on a toolholder pocket.Thus, the cutting insert 200 would eliminate or reduce the need forcreating multiple cutting inserts having differing number of grooves tosatisfying differing requirements regarding depth of cut and number ofrotations of the cutting insert upon repositioning.

In an aspect, the lug offset angle is in a range of from 14 to 32degrees. In a first example, the lug offset angle is in a range of from14 to 16 degrees, preferably 15 degrees. In a second example, the lugoffset angle is in a range of from 19 to 21 degrees, preferably 20degrees. In a third example, the lug offset angle is in a range of from29 to 31 degrees, preferably 30 degrees.

A lug offset angle of about 15, about 20, or about 30 degrees isbeneficial because these degree lug offset angles are twice of thegroove offset angles of about 7.5, about 10, and about 15, and thusalternating grooves in the pocket floor may be engaged with lugs of thecutting insert to ensure high resistance against rotation of the cuttinginsert. A lug offset angle of three times the number of grooves, i.e.,about 22.5 degrees, about 30 degrees, or about 45 degrees, or a lugoffset angle of four times the number of grooves, i.e. about 30 degrees,about 40 degrees, or about 60 degrees, etc., would also function, butwould result in less engagement between grooves in the pocket floor andlugs of the cutting insert.

Also, a lug offset angle of 30 degrees is beneficial because the 30degree lug offset provides for enough clearance between lugs for ease ofmanufacturing during a process of machining the lugs at the bottom ofthe cutting insert. A smaller lug offset angle of about 20 degrees orabout 15 degrees would also function but machining of the lugs would beincreasingly challenging.

The lower surface 220 may include landing 222 extending about aperiphery of the lower surface 220. The landing 222 may function toengage with the base 118 of the pocket floor 112 to support the cuttinginsert 200 when fastened within the toolholder pocket 110. The landing222 may typically take the form a generally planar surface. The landing222 may having a landing width 223 sufficient to support the cuttinginsert 200 when fastened within the toolholder pocket 110.

The plurality of lugs 221 on the lower surface 220 may be positionedwithin a depressed cavity 224 that is depressed relative to the landing222. By positioning the plurality of lugs 221 within the cavity 224, thecutting insert 200 may be primarily supported by the landing 222 whenfastened within the toolholder pocket 110, and the plurality of lugs 221may primarily function to prevent unintended rotation of the cuttinginsert 200 within the toolholder pocket 110.

Each lug 221 may be defined by a structure of the cutting insert 200extending from a trough 225 to a crest 226 to an adjacent trough 225,having a height 227 and length 228. The height 227 corresponds to adepth of the grooves 120 in the pocket floor 112. Thus, the lugs havefirst lug engagement surfaces that corresponds to the first segmentengagement surfaces 122 and second lug engagement surfaces thatcorresponds to the second segment engagement surfaces 123. The lugs maydefine a maximum angular lug width 229, which is defined in terms ofdegrees about the aperture 241. In an aspect, the maximum angularsegment width 229 of each lug 221 may be less than the groove offsetangle x to facilitate a maximum density of lugs 221 and segments 121 andto avoid interference of the lugs 221 with the segments 121 duringplacement of the cutting insert 200 within the pocket floor 112 of thetoolholder 100.

With references to FIGS. 8 and 9 , the present description includes amethod for repositioning the round cutting insert 200 in the toolholderpocket 110. FIG. 8 illustrates the cutting insert 200 fully fastenedwithin the toolholder pocket 110 by fastener 300. FIG. 9 illustrates thecutting insert 200 partially unfastened from the toolholder pocket 110such the plurality of lugs 221 are capable of being disengaged with theplurality of grooves 120 by lifting the cutting insert 200 away from thepocket floor 112. Alternatively, the cutting insert 200 may be fullyunfastened from the toolholder pocket 110. Once the plurality of lugs221 are disengaged with the plurality of grooves 120, the round cuttinginsert may be rotated by a rotation angle z and then the cutting insert200 may be again fully fastened within the toolholder pocket 110 byfastener 300.

In the case that the groove offset angle is, in the first example, about15 degrees, the cutting insert 200 may be rotated by a rotation angle zin increments of 15 degrees. Thus, the cutting insert 200 may be rotatedby, for example, a rotation angle z of about 45 degrees to provide for 8total of rotations before replacement of the cutting insert.Alternatively, the same cutting insert 200 may be rotated by a rotationangle z of about 60 degrees to provide for 6 total of rotations beforereplacement of the cutting insert. Alternatively, the same cuttinginsert 200 may be rotated by a rotation angle z of about 90 degrees toprovide for 4 total of rotations before replacement of the cuttinginsert.

In the case that the groove offset angle is, in the second example,about 10 degrees, the cutting insert 200 may be rotated by a rotationangle z in increments of 10 degrees. Thus, the cutting insert 200 may berotated by, for example, a rotation angle z of about 40 degrees toprovide for 9 total of rotations before replacement of the cuttinginsert. Alternatively, the same cutting insert 200 may be rotated by arotation angle z of about 60 degrees to provide for 6 total of rotationsbefore replacement of the cutting insert. Alternatively, the samecutting insert 200 may be rotated by a rotation angle z of about 90degrees to provide for 4 total of rotations before replacement of thecutting insert.

In the case that the groove offset angle is, in the third example, about7.5 degrees, the cutting insert 200 may be rotated by a rotation angle zin increments of 7.5 degrees. Thus, the cutting insert 200 may berotated by, for example, a rotation angle z of about 22.5 degrees toprovide for 16 total of rotations before replacement of the cuttinginsert. Alternatively, the same cutting insert 200 may be rotated by arotation angle z of about 30 degrees to provide for 12 total ofrotations before replacement of the cutting insert. Alternatively, thesame cutting insert 200 may be rotated by a rotation angle z of about 45degrees to provide for 8 total of rotations before replacement of thecutting insert.

Thus, the toolholder 100 and cutting insert 200 of the presentdescription provide for a single cutting tool 10 that provides for adurable and effective anti-rotation mechanism while providingflexibility for the user to select a number of total desired rotations(e.g., 4 rotations, 6 rotations, 8 rotations) depending on the desireddepth of the cut for the machining operation.

Although various embodiments of the disclosed cutting tool have beenshown and described, modifications may occur to those skilled in the artupon reading the specification. The present application includes suchmodifications and is limited only by the scope of the claims.

What is claimed is:
 1. A cutting tool, comprising: a toolholdercomprising: a toolholder pocket floor having a bore therein; and aplurality of grooves in the pocket floor arranged radially about thebore, wherein adjacent grooves are radially offset by a groove offsetangle x; and a round cutting insert for mounting on the toolholderpocket floor, the round cutting insert comprising: an upper surfacehaving a cutting edge; a lower surface opposite the upper surface, thelower surface comprising a landing extending about a periphery of thelower surface; an exterior side surface between the upper surface andthe lower surface; an interior side surface defining an apertureextending from the upper surface to the lower surface; and a pluralityof lugs arranged radially about the aperture, wherein adjacent lugs areradially offset by a lug offset angle y, and wherein a ratio of y:x isan integer greater than or equal to 2, and wherein the plurality of lugsare positioned within a depressed cavity that is depressed relative tothe landing.
 2. The cutting tool of claim 1, wherein the groove offsetangle is in a range of 7 to 17 degrees.
 3. The cutting tool of claim 1,wherein the ratio of y:x is 2, 3, or
 4. 4. The cutting tool of claim 1,wherein the ratio of y:x is
 2. 5. A method for repositioning the roundcutting insert in the toolholder for the cutting tool of claim 1, themethod comprising: partially or fully unfastening the round cuttinginsert from a toolholder pocket of the toolholder; rotating the roundcutting insert by a rotation angle z; and fastening the round cuttinginsert in the toolholder pocket.
 6. The method of claim 1, wherein therotation angle is about 45 degrees.
 7. The method of claim 1, whereinthe rotation angle is about 60 degrees.
 8. The method of claim 1,wherein the rotation angle is about 90 degrees.
 9. A round cuttinginsert, comprising: an upper surface having a cutting edge; a lowersurface opposite the upper surface, the lower surface comprising alanding extending about a periphery of the lower surface; an exteriorside surface between the upper surface and the lower surface; aninterior side surface defining an aperture extending from the uppersurface to the lower surface, the aperture having a central axisextending from the lower surface to the upper surface; and a pluralityof lugs arranged radially about the aperture adjacent to the landing,wherein adjacent lugs are radially offset by a lug offset angle y, andwherein the plurality of lugs are positioned within a depressed cavitythat is depressed relative to the landing, and wherein each of theplurality lugs comprises a trough and a crest extending from the troughalong the central axis.